Method of forming conductive grid of integrated circuit

ABSTRACT

A method of forming an integrated circuit includes: forming a conductive grid on a semiconductor substrate; selecting a plurality of first conductive lines from a plurality of non-continuous conductive lines according to a first mask layer assigned to the plurality of first conductive lines; selecting a plurality of second conductive lines from the plurality of non-continuous conductive lines according to a second mask layer assigned to the plurality of second conductive lines, wherein the second mask layer different from the first mask layer, and the plurality of second conductive lines is electrically connected to the plurality of first conductive lines via the plurality of continuous conductive lines; and replacing the plurality of second conductive lines by a plurality of third conductive lines respectively, wherein the plurality of third conductive lines is assigned to the first mask layer.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.62/590,051, filed Nov. 22, 2017.

BACKGROUND

The electric current used by various active semiconductor devices in asemiconductor chip are distributed through a set of electricinterconnects or a power grid of the semiconductor chip. Therefore, thepower grid is the power delivering structure in the semiconductor chip.A power grid may spread across different conductive levels, and may ingeneral provide electric power or current to the various semiconductordevices using conductive wires, paths, pathways at different levels,and/or vias in crossing different levels. Currently, there arechallenges to further improve the performance of the voltage (IR) drop,electro-migration (EM) performance, and routing resource of a power gridof a semiconductor chip.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 is a cross-sectional diagram illustrating a power grid of anintegrated circuit in accordance with some embodiments.

FIG. 2 is a top-view diagram illustrating a power grid of an integratedcircuit in accordance with some embodiments.

FIG. 3 is a top-view diagram illustrating a related art of a power grid.

FIG. 4 is a flow chart illustrating a method of forming a power grid ofan integrated circuit in accordance with some embodiments.

FIG. 5 is a diagram illustrating a power grid layout design inaccordance with some embodiments.

FIG. 6 is a diagram illustrating a power grid layout design inaccordance with some embodiments.

FIG. 7 is a flow chart illustrating a method of forming a power grid ofan integrated circuit in accordance with some embodiments.

FIG. 8A is a diagram illustrating a layout portion in the power gridlayout design of FIG. 5 in accordance with some embodiments.

FIG. 8B is a diagram illustrating a layout portion in the power gridlayout design of FIG. 6 in accordance with some embodiments.

FIG. 9A is a diagram illustrating a layout portion in the power gridlayout design of FIG. 5 in accordance with some embodiments.

FIG. 9B is a diagram illustrating a layout portion in the power gridlayout design of FIG. 6 in accordance with some embodiments.

FIG. 10 is a diagram of a hardware system for implementing a method togenerate a power grid layout design in accordance with some embodiments.

FIG. 11 is a diagram of a system for fabricating a power grid inaccordance with some embodiments.

FIG. 12 is a flowchart of a chip design flow and a chip manufacturingflow of an integrated circuit chip in accordance with some embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Embodiments of the present disclosure are discussed in detail below. Itshould be appreciated, however, that the present disclosure providesmany applicable inventive concepts that can be embodied in a widevariety of specific contexts. The specific embodiments discussed aremerely illustrative and do not limit the scope of the disclosure.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper”, “lower”, “left”, “right” and the like, may be usedherein for ease of description to describe one element or feature'srelationship to another element(s) or feature(s) as illustrated in thefigures. The spatially relative terms are intended to encompassdifferent orientations of the device in use or operation in addition tothe orientation depicted in the figures. The apparatus may be otherwiseoriented (rotated 90 degrees or at other orientations) and the spatiallyrelative descriptors used herein may likewise be interpretedaccordingly. It will be understood that when an element is referred toas being “connected to” or “coupled to” another element, it may bedirectly connected to or coupled to the other element, or interveningelements may be present.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the disclosure are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contains certainerrors necessarily resulting from the standard deviation found in therespective testing measurements. Also, as used herein, the term “about”generally means within 10%, 5%, 1%, or 0.5% of a given value or range.Alternatively, the term “about” means within an acceptable standarderror of the mean when considered by one of ordinary skill in the art.Other than in the operating/working examples, or unless otherwiseexpressly specified, all of the numerical ranges, amounts, values andpercentages such as those for quantities of materials, durations oftimes, temperatures, operating conditions, ratios of amounts, and thelikes thereof disclosed herein should be understood as modified in allinstances by the term “about.” Accordingly, unless indicated to thecontrary, the numerical parameters set forth in the present disclosureand attached claims are approximations that can vary as desired. At thevery least, each numerical parameter should at least be construed inlight of the number of reported significant digits and by applyingordinary rounding techniques. Ranges can be expressed herein as from oneendpoint to another endpoint or between two endpoints. All rangesdisclosed herein are inclusive of the endpoints, unless specifiedotherwise.

FIG. 1 is a cross-sectional diagram illustrating a power grid 100 of anintegrated circuit 102 in accordance with some embodiments. The powergrid 100 is a conductive grid arranged to deliver power from powersource to a plurality of semiconductor cells (e.g. 104 and 106) in theintegrated circuit 102. The power grid 100 is also arranged to conductthe plurality of semiconductor cells 104 and 106 to the ground voltage.The power grid 100 may be formed on back end of the line (BEOL) of theintegrated circuit 102. According to some embodiments, the power grid100 may comprise metal lines formed in the metal layers M0, M1, M2, M3,and via structures formed between the metal layers M0 and M1, the metallayers M1 and M2, and the metal layers M2 and M3. It is noted that thenumber of metal layers is just an example of the embodiment, and this isnot a limitation of the embodiment. In addition, the metal lines and thevia structures of the power grid 100 may be composed of various type ofconductive material. For example, the conductive material may beselected from a group consisting of tungsten (W), aluminum (Al), copper(Cu), silver (Ag), gold (Au), titanium (Ti), tantalum (Ta), ruthenium(Ru), tungsten (W), titanium-nitride (TiN), tantalum-nitride (TaN),ruthenium nitride (RuN), and tungsten nitride (WN), and alloy thereof.The interlayers separated the metal layers M0, M1, M2, M3 are composedof insulating material. For example, the insulating material may bedielectric material.

FIG. 2 is a top-view diagram illustrating a power grid 200 of anintegrated circuit 202 in accordance with some embodiments. The powergrid 200 comprises a plurality of vertical metal lines 204 a, 204 b, 204c, 204 d, 204 e, 204 f in metal layer M3, and a plurality of horizontalmetal lines 206 a, 206 b, 206 c, 206 d, 206 e, 206 f, 206 g, 206 h, 206i in metal layer M2. In addition, the power grid 200 further comprises aplurality of via structures 208 a, 208 b, 208 c, 208 d, 208 e, 208 f,208 g, 208 h, 208 i for connecting the corresponding metal lines in themetal layers M3 and M2. Specifically, the via structure 208 a isarranged to connect the metal lines 204 a and 206 a. The via structure208 b is arranged to connect the metal lines 204 d and 206 b. The viastructure 208 c is arranged to connect the metal lines 204 e and 206 c.The via structure 208 d is arranged to connect the metal lines 204 b and206 d. The via structure 208 e is arranged to connect the metal lines204 c and 206 e. The via structure 208 f is arranged to connect themetal lines 204 f and 206 f. The via structure 208 g is arranged toconnect the metal lines 204 a and 206 g. The via structure 208 h isarranged to connect the metal lines 204 d and 206 h. The via structure208 i is arranged to connect the metal lines 204 e and 206 i. It isnoted that, FIG. 2 merely labeled out the metal lines in metal layers M3and M2 and the via structures connecting metal lines in the metal layersM3 and M2, and the metal lines in metal layers M1 and M0 are not labeledfor brevity.

According to some embodiments, the plurality of vertical metal lines 204a, 204 b, 204 c, 204 d, 204 e, and 204 f are continuous metal linesdisposed on vertical direction in FIG. 2, and the plurality ofhorizontal metal lines 206 a, 206 b, 206 c, 206 d, 206 e, 206 f, 206 g,206 h, and 206 i are non-continuous metal lines disposed on horizontaldirection in FIG. 2. For example, the plurality of vertical metal lines204 a, 204 b, 204 c, 204 d, 204 e, and 204 f are continuous metal linesextending to the lower bound 216 from the upper bound 214 of the powergrid 200. The plurality of horizontal metal lines 206 a, 206 b, and 206c, as well as the metal lines 206 d, 206 e, 206 f and the metal lines206 g, 206 h, 206 i, are arranged to non-continuously extending to theright side from the left side of the power grid 200. It is noted that,in FIG. 2, the vertical direction is orthogonal to the horizontaldirection.

According to some embodiments, the plurality of vertical metal lines 204a, 204 d, and 204 e are electrically connected to supply voltage orpower source, and the plurality of vertical metal lines 204 b, 204 c,and 204 f are electrically connected to ground voltage. The verticalmetal lines 204 a and 204 b are neighboring metal lines. The verticalmetal lines 204 c and 204 d are neighboring metal lines. The verticalmetal lines 204 e and 204 f are neighboring metal lines. The space withthe width S1 between two neighboring metal lines is greater than thespace with the width S2 between the neighboring metal lines. Therefore,the power grid 200 may be an non-uniform power grid structure.

According to some embodiments, the metal lines 206 a, 206 b, 206 c, 206g, 206 h, and 206 i are arranged to have the same length L1, and themetal lines 206 d, 206 d, and 206 f are arranged to have the same lengthL2. The length L2 is greater than the length L1.

In addition, the horizontal space between the two adjacent metal lines(e.g. the space between the metal lines 206 b and 206 c) selected fromthe metal lines 206 a, 206 b, 206 c, 206 g, 206 h, and 206 i has thewidth S3. The horizontal space between the two adjacent metal lines(e.g. the space between the metal lines 206 e and 206 f) selected fromthe metal lines 206 d, 206 e, and 206 f has the width S4. The width S3is greater than the width S4. According to some embodiments, the spacewith the width S3 is wide enough for a metal line or signal route topass through. For example, a signal route 210 is arranged to passthrough the space between the metal lines 206 a and 206 b, and a signalroute 212 is be arranged to pass through the space between the metallines 206 b and 206 c. In addition, a signal route (not shown) may bearranged to pass through the space between the metal lines 206 g and 206h, and a signal route (not shown) may be arranged to pass through thespace between the metal lines 206 h and 206 i. It is noted that thesignal routes (e.g. 210) are formed in the metal layer M0 and may beelectrically connected other metal layer through conductive vias. On theother hand, the space with the width S4 is too narrow for a metal lineor signal route to pass through. Therefore, there is not signal route topass through the space between the metal lines 206 d and 206 e and thespace between the metal lines 204 e and 204 f.

FIG. 3 is a top-view diagram illustrating a related art of a power grid300. The power grid 300 is a counterpart of the power grid 200. Forbrevity, some numerals in the power grid 300 are similar to the numeralsin the power grid 200. The elements of the power grid 300 having thesame numerals with those in the power grid 200 also have the similarcharacteristic. In the power grid 300, the lengths (i.e. L2) of themetal lines 306 a, 306 b, and 306 c are similar to the lengths (i.e. L2)of the metal lines 206 d, 206 e, and 206 f respectively. Therefore, thespace (i.e. S4) between the metal lines 306 a and 306 b is similar tothe space (i.e. S4) between the metal lines 206 d and 206 e, and thespace (i.e. S4) between the metal lines 306 b and 306 c is similar tothe space (i.e. S4) between the metal lines 206 e and 206 f. Asmentioned above, the space with S4 is too narrow for a metal line orsignal route to pass through. Therefore, there is not signal route topass through the space between the metal lines 306 a and 306 b and thespace between the metal lines 306 b and 306 c.

Accordingly, in comparison to the power grid 300, the present power grid200 provides extra space (e.g. the space between the metal lines 206 aand 206 b and the space between the metal lines 206 b and 206 c) forsignal net routing on the BEOL of the integrated circuit 102. Therefore,in comparison to the power grid 300, the routing resource of the powergrid 200 is increase.

FIG. 4 is a flow chart illustrating a method 400 of forming a power grid(e.g. 200) of an integrated circuit in accordance with some embodiments.The method 400 is arranged to perform on a power grid layout design. Themethod 400 comprises operations 402˜406.

In operation 402, a power grid layout design 500 is provided. FIG. 5 isa diagram illustrating the power grid layout design 500 in accordancewith some embodiments. The power grid layout design 500 may be createdby a layout creating software. The power grid layout design 500 may beprocessed by a processor and displayed on a display tool. According tosome embodiments, the power grid layout design 500 a plurality ofvertical metal lines 504 a, 504 b, 504 c, 504 d, 504 e, 504 f in metallayer M3, and a plurality of horizontal metal lines 506 a, 506 b, 506 c,506 d, 506 e, 506 f, 506 g, 506 h, 506 i in metal layer M2. In addition,the power grid layout design 500 further comprises a plurality of viastructures 508 a, 508 b, 508 c, 508 d, 508 e, 508 f, 508 g, 508 h, 508 ifor connecting the corresponding metal lines in the metal layers M3 andM2.

The via structure 508 a is arranged to connect the metal lines 504 a and506 a. The via structure 508 b is arranged to connect the metal lines504 d and 506 b. The via structure 508 c is arranged to connect themetal lines 504 e and 506 c. The via structure 508 d is arranged toconnect the metal lines 504 b and 506 d. The via structure 508 e isarranged to connect the metal lines 504 c and 506 e. The via structure508 f is arranged to connect the metal lines 504 f and 506 f. The viastructure 508 g is arranged to connect the metal lines 504 a and 506 g.The via structure 508 h is arranged to connect the metal lines 504 d and506 h. The via structure 508 i is arranged to connect the metal lines504 e and 506 i.

According to some embodiments, although the horizontal metal lines 506a, 506 b, 506 c, 506 d, 506 e, 506 f, 506 g, 506 h, 506 i are formed inthe same metal layer (i.e. the metal layer M2), the metal lines 506 a,506 b, 506 c, 506 d, 506 e, 506 f are assigned to or masked by a firstmask layer, and the metal lines 506 g, 506 h, 506 i are assigned to asecond mask layer during the manufacturing process. The second masklayer is different from the first mask layer. The first mask layer doesnot have the function of cut-metal while the second mask layer has thefunction of cut-metal. The function of cut-metal may be carried out by acut-metal pattern. A cut-metal pattern is a layer for removing a portionof a metal line when the cut-metal pattern overlaps the portion of themetal line.

In addition, when the metal lines 506 a, 506 b, 506 c, 506 d, 506 e, 506f are assigned by the first mask layer, the metal lines 506 a, 506 b,506 c, 506 d, 506 e, 506 f are displayed by a first color (e.g. red) onthe display tool. When the metal lines 506 g, 506 h, 506 i are assignedby the second mask layer, the metal lines 506 g, 506 h, 506 i aredisplayed by a second color (e.g. pink) different from the first coloron the display tool.

According to some embodiments, the power grid layout design 500 furthercomprises a plurality of cut-metal patterns 510 a, 510 b, 510 c, 510 d,510 e, and 510 f. The cut-metal patterns 510 a and 510 b are disposed ona first end and a second end of the metal line 506 g. The cut-metalpatterns 510 c and 510 d are disposed on a first end and a second end ofthe metal line 506 h. The cut-metal patterns 510 e and 510 f aredisposed on a first end and a second end of the metal line 506 h. Therehas no cut-metal pattern disposed on the metal lines 506 a, 506 b, 506c, 506 d, 506 e, 506 f. As a portion of each of the metal lines 506 g,506 h, and 506 i is removed by the corresponding cut-metal pattern, thelength L2 of each of the cut-metal patterns 510 a, 510 b, 510 c, 510 d,510 e, and 510 f is greater than the length L1 of each of the metallines 506 g, 506 h, and 506 i if the power grid layout design 500 isfabricated (e.g. the power grid 300 as shown in FIG. 3).

In the power grid layout design 500, the space between the metal lines506 a and 506 b and the space the metal lines 506 b and 506 c are S4,which is smaller than the space (i.e. S3) between the metal lines 506 gand 506 h and the space between the metal lines 506 h and 506 i.Therefore, there is not signal route to pass through the space betweenthe metal lines 506 a and 506 b and the space between the metal lines506 b and 506 c.

It is noted that, FIG. 5 merely labeled out the metal lines in metallayers M3 and M2 and the via structures inter-connecting the metal linesin the metal layers M3 and M2, and the metal lines in metal layers M1and M0 are not labeled for brevity.

In operation 404, the metal lines 506 g, 506 h, and 506 i assigned tothe second mask layer, and the metal lines 506 a, 506 b, and 506 cassigned to the first mask layer are selected.

In operation 406, the first mask layer of the metal lines 506 a, 506 b,and 506 c is replaced by or changed to the second mask layer. FIG. 6 isa diagram illustrating the power grid layout design 600 in accordancewith some embodiments. As shown in FIG. 6, when the metal lines 506 a,506 b, and 506 c is replaced by the second mask layer, a plurality ofcut-metal patterns 602 a, 602 b, 602 c, 602 d, 602 e, and 602 f aredisposed on the first ends and the second ends of the metal lines 506 a,506 b, and 506 c. For brevity, the metal lines 506 a, 506 b, and 506 care re-numbered into 604 a, 604 b, and 606 c respectively in FIG. 6.When the cut-metal patterns 602 a, 602 b, 602 c, 602 d, 602 e, and 602 fare disposed on the first ends and the second ends of the metal lines604 a, 604 b, and 604 c respectively, the length of each of the metallines 604 a, 604 b, and 604 c may be reduced from L2 to L1, which issimilar to the length of the metal lines 506 g, 506 h, and 506 i.Accordingly, in the power grid layout design 600, the space between themetal lines 604 a and 604 b and the space the metal lines 604 b and 604c are S3, which is similar to the space (i.e. S3) between the metallines 506 g and 506 h and the space between the metal lines 506 h and506 i. Therefore, signal routes may pass through the space between themetal lines 604 a and 604 b and the space between the metal lines 604 band 604 c.

Accordingly, when the metal lines 604 a, 604 b, and 604 c are assignedto the second mask layer, the metal lines 604 a, 604 b, and 604 c aredisplayed by the second color (e.g. pink) on the display tool.

FIG. 7 is a flow chart illustrating a method 700 of forming a power grid(e.g. 200) of an integrated circuit in accordance with some embodiments.The method 700 is arranged to perform on the power grid layout design500. The method 700 comprises operations 702˜706. For brevity, theoperation of method 700 is described by using the above FIG. 5 and FIG.6.

In operation 702, the power grid layout design 500 is provided. As thepower grid layout design 500 has been described in above paragraphs, thedetailed description is omitted here for brevity.

In operation 704, the metal lines 506 a, 506 b, and 506 c, 506 d, 506 e,and 506 f assigned to the first mask layer are selected.

In operation 706, the first mask layer of the metal lines 506 a, 506 b,and 506 c is replaced by or changed to the second mask layer as shown inFIG. 6. As shown in FIG. 6, the metal lines 506 a, 506 b, and 506 c arere-numbered into 604 a, 604 b, and 606 c respectively. When thecut-metal patterns 602 a, 602 b, 602 c, 602 d, 602 e, and 602 f aredisposed on the first ends and the second ends of the metal lines 604 a,604 b, and 604 c respectively, the length of each of the metal lines 604a, 604 b, and 604 c may be reduced from L2 to L1, which is similar tothe length of the metal lines 506 g, 506 h, and 506 i. Accordingly, inthe power grid layout design 600, the space between the metal lines 604a and 604 b and the space the metal lines 604 b and 604 c are S3, whichis similar to the space (i.e. S3) between the metal lines 506 g and 506h and the space between the metal lines 506 h and 506 i. Therefore,signal routes may pass through the space between the metal lines 604 aand 604 b and the space between the metal lines 604 b and 604 c.

According to some embodiments, when the metal lines 506 a, 506 b, and506 c are changed to the second mask layer from the first mask layer,the positions of the metal lines 604 a, 604 b, and 604 c may not be thesame positions to the metal lines 506 a, 506 b, and 506 c respectively.In other words, the positions of the metal lines 604 a, 604 b, and 604 cmay deviate from the original positions of the metal lines 506 a, 506 b,and 506 c respectively. However, this deviation may not affect thepredetermined function of the power grid layout design 600.

FIG. 8A is a diagram illustrating a layout portion 512 in the power gridlayout design 500 in accordance with some embodiments. FIG. 8B is adiagram illustrating a layout portion 612 in the power grid layoutdesign 600 in accordance with some embodiments. For the sake ofcomparison, the location of the layout portion 612 corresponds to thelocation of the layout portion 512. In the layout portion 512 as well asthe layout portion 612, a site row 802 is formed on the metal line 804,wherein the metal line 804 is formed in the metal layer M1. It is notedthat the metal line 506 c as well as the metal line 604 c are formed inthe metal layer M2. Moreover, a site row is a line where two or morestandard cells abut vertically. A cut-metal pattern 806 is disposed onone end of the metal line 804, and the other cut-metal pattern 808 isdisposed on the other end of the metal line 804.

In addition, in the layout portion 512 as well as the layout portion612, there has three dotted lines 810, 812, and 814 in parallel to thesite row 802. The dotted line 810 is slightly above the site row 802.For example, the dotted line 810 may be +20 nm offset from the site row802. The dotted line 810 or 814 are the locations for forming the metalline 506 c by using the first mask layer. The dotted line 812 is thelocation for forming the metal line 604 c by using the second masklayer. According to some embodiments, the metal line 506 c assigned tothe first mask layer is formed on the dotted line 810. When the metalline 506 c is re-assigned to the second mask layer, the position of there-assigned metal line 604 c is changed to the dotted line 812 as shownin FIG. 8B. It is noted that as long as the metal line 604 c is locatedin the area between the dotted lines 810 and 814, the metal line 604 cmay electrically connected to the metal line formed in the metal layerMO, which is disposed under the metal layer Ml, in order to deliverpower from power source to the corresponding semiconductor cell in theintegrated circuit.

FIG. 9A is a diagram illustrating a layout portion 512 in the power gridlayout design 500 in accordance with some embodiments. FIG. 9B is adiagram illustrating a layout portion 612 in the power grid layoutdesign 600 in accordance with some embodiments. Similar to FIG. 8A andFIG. 8B, the location of the layout portion 612 corresponds to thelocation of the layout portion 512. In the layout portion 512 as well asthe layout portion 612, a site row 802 is formed on the metal line 804,wherein the metal line 804 is formed in the metal layer M1. It is notedthat the metal line 506 c as well as the metal line 604 c are formed inthe metal layer M2. A cut-metal pattern 806 is disposed on one end ofthe metal line 804, and the other cut-metal pattern 808 is disposed onthe other end of the metal line 804.

In comparison to FIG. 8A and FIG. 8B, the locations of the dotted lines910, 912, and 914 are different from the dotted lines 810, 812, and 814.In FIG. 9A and FIG. 9B, the dotted line 914 is slightly below the siterow 802. For example, the dotted line 914 may be −20 nm offset from thesite row 802. The dotted line 910 or 914 are the locations for formingthe metal line 506 c by using the first mask layer. The dotted line 912is the location for forming the metal line 604 c by using the secondmask layer.

According to some embodiments, the metal line 506 c assigned to thefirst mask layer is formed on the dotted line 914. When the metal line506 c is re-assigned to the second mask layer, the position of there-assigned metal line 604 c is changed to the dotted line 912 as shownin FIG. 9B. It is noted that as long as the metal line 604 c is locatedin the area between the dotted lines 910 and 914, the metal line 604 cmay electrically connected to the metal line formed in the metal layerM0, which is disposed under the metal layer M1, in order to deliverpower from power source to the corresponding semiconductor cell in theintegrated circuit.

FIG. 10 is a diagram of a hardware system 1000 for implementing themethod 400 to generate the power grid layout design 600 in accordancewith some embodiments. The system 2500 includes at least one processor1002, a network interface 1004, an input and output (I/O) device 1006, astorage 1008, a memory 1012, and a bus 1010. The bus 1010 couples thenetwork interface 1004, the I/O device 1006, the storage 1008 and thememory 1012 to the processor 1002.

In some embodiments, the memory 1012 comprises a random access memory(RAM) and/or other volatile storage device and/or read only memory (ROM)and/or other non-volatile storage device. The memory 1012 includes akernel 1016 and user space 1014, configured to store programinstructions to be executed by the processor 1002 and data accessed bythe program instructions.

In some embodiments, the network interface 1004 is configured to accessprogram instructions and data accessed by the program instructionsstored remotely through a network. The I/O device 1006 includes an inputdevice and an output device configured for enabling user interactionwith the system 1000. The input device comprises, for example, akeyboard, a mouse, etc. The output device comprises, for example, adisplay, a printer, etc. The storage device 1008 is configured forstoring program instructions and data accessed by the programinstructions. The storage device 1008 comprises, for example, a magneticdisk and an optical disk.

In some embodiments, when executing the program instructions, theprocessor 1002 is configured to perform the operations of the method 400(or 700) as described with reference to FIG. 4 (or FIG. 7).

In some embodiments, the program instructions are stored in anon-transitory computer readable recording medium such as one or moreoptical disks, hard disks and non-volatile memory devices.

FIG. 11 is a diagram of a system 1100 for fabricating the power grid 300in accordance with some embodiments. The system 1100 comprises acomputing system 1102 and a fabricating tool 1104. The computing system1102 is arranged to perform operations of the method 400 (or 700) togenerate the power grid layout design 600. The computing system 1102 maybe the above system 1000. The fabricating tool 1104 may be a clustertool for fabricating a integrated circuit. The cluster tool may be amultiple reaction chamber type composite equipment which includes apolyhedral transfer chamber with a wafer handling robot inserted at thecenter thereof, a plurality of process chambers positioned at each wallface of the polyhedral transfer chamber; and a loadlock chamberinstalled at a different wall face of the transfer chamber. At thefabrication stage, at least one photomask is used, for example, for onepatterning operation for forming a feature of ICs, such as gate lines oftransistors, source or drain regions for the transistors, metal linesfor interconnects and vias for the interconnects, on a wafer.

FIG. 12 is a flowchart of a chip design flow 1202 and a chipmanufacturing flow 1204 of an integrated circuit (IC) chip in accordancewith some embodiments. The chip design flow 1202 implements an IC chipdesign from a high-level specification to a physical layout which isverified for, for example, functionality, performance, and power, and istapped out for production of masks. One or more electronic designautomation (EDA) tools is arranged to carry out one or more stages oroperations in the flows of the chip design flow 1202. The chipmanufacturing flow 1204 manufactures the IC chip using the masks.

In some embodiments, the chip design flow 1202 includes a system designstage 1202 a, a logic design stage 1202 b, a logic synthesis stage 1202c, a physical implementation 1202 d, a parasitic extraction stage 1202 eand a physical verification and electrical signoff stage 1202 f, and atape out stage 1202 g.

At the system design stage 1202 a, the designer describes the IC chip interms of larger modules that serve specific functions, respectively.Further, exploration for options include design architectures isperformed to consider, for example, tradeoffs in optimizing designspecifications and cost.

At the logic design stage 1202 b, the modules for the IC chip aredescribed at the register transfer level (RTL) using the VHDL orVerilog, and are verified for functional accuracy.

At the logic synthesis stage 1202 c, the modules for the IC chipdescribed in RTL are translated into a gate-level netlist. Technologymapping of the logic gates and registers to available cells in thecreated standard cell library from the cell design flow 100 also happenat this stage.

At the physical implementation stage 1202 d, the gate-level netlist ispartitioned into blocks and a floorplan for the blocks is created for adesign layout. Mapped cells of logic gates and registers in the blocksare placed at specific locations in the design layout. Router-routedinterconnects connecting the placed cells are created. In someembodiments, during placement and routing, total wire length, wiringcongestion and/or timing are optimized. Using the combined cellsfacilitates such optimization.

At the parasitic extraction stage 1202 e, a physical netlist isextracted from the design layout. The physical netlist includesparasitics such as parasitic resistors and capacitors introduced by theinterconnects to the cells.

At the physical verification and electrical signoff stage 1202 f, timinganalysis and post-route optimization are performed on the physicalnetlist to ensure timing closure. The design layout is checked to ensureclean of, for example, design rule check (DRC) issues, layout versusschematic issues (LVS) and electrical rule check (ERC) issues.Incremental fixing can be performed to achieve electrical signoff of theIC design.

At the tapeout stage 1202 g, the design layout is checked to ensureclean of, for example, photolithography issues and is modified using,for example, optical proximity correction (OPC) techniques. For eachlayer in the final design layout, a corresponding photomask, forexample, is created for manufacturing of the IC chip. According to someembodiments, the first mask layer and the second mask layer as mentionedin the operation 406 are fabricated in this stage. The first mask layeris arranged have patterns corresponding to the metal lines 506 d, 506 e,and 506 f. The second mask layer is arranged to have patternscorresponding to the metal lines 604 a, 604 b, 604 c, 506 g, 506 h, and506 i.

In some embodiments, the chip manufacturing flow 1204 includes afabrication stage 1204 a and a packaging and testing stage 1204 b.

At the fabrication stage 1204 a, the photomask(s) is used, for example,for one patterning operation for forming a feature of ICs, such as gatelines of transistors, source or drain regions for the transistors, metallines for interconnects and vias for the interconnects, on a wafer.According to some embodiments, the first mask layer is arranged to formthe metal lines 506 d, 506 e, and 506 f. The second mask layer isarranged to form the metal lines 604 a, 604 b, 604 c, 506 g, 506 h, and506 i.

At the packaging and assembly stage 1204 b, ICs on the wafer are dicedinto IC chips and are packaged considering, for example, protection frommechanical damaging, cooling, electromagnetic interference andprotection from electrostatic discharge. An IC chip may be assembledwith other components for use.

The chip design flow 1202 and the chip manufacturing flow 1204 in FIG.12 are exemplary. Other sequences of the stages or sequences ofoperations in the stages, or additional stages or operations before,between or after the stages shown are within the applicable scope of thepresent disclosure.

Briefly, by using the proposed methods, the lengths of some horizontalmetal lines in a power grid of an integrated circuit are reduced.Accordingly, the size of the power grid is reduced. Moreover, the powergrid also provides extra space for signal net routing on the BEOL of theintegrated circuit.

According to some embodiments, a method of forming an integrated circuitis provided. The method comprises: forming a conductive grid on asemiconductor substrate, wherein the conductive grid has a plurality ofcontinuous conductive lines arranged in a first direction on a firstconductive layer and a plurality of non-continuous conductive linesarranged in a second direction on a second conductive layer; selecting aplurality of first conductive lines from the plurality of non-continuousconductive lines according to a first mask layer assigned to theplurality of first conductive lines; selecting a plurality of secondconductive lines from the plurality of non-continuous conductive linesaccording to a second mask layer assigned to the plurality of secondconductive lines, wherein the second mask layer different from the firstmask layer, and the plurality of second conductive lines is electricallyconnected to the plurality of first conductive lines via the pluralityof continuous conductive lines; and replacing the plurality of secondconductive lines by a plurality of third conductive lines respectivelywhen the plurality of first conductive lines has a cut-metal pattern andthe plurality of second conductive lines does not have the cut-metalpattern, wherein the plurality of third conductive lines is assigned tothe first mask layer.

According to some embodiments, a method of forming an integrated circuitis provided. The method comprises: forming a conductive grid on asemiconductor substrate, wherein the conductive grid has a plurality ofcontinuous conductive lines arranged in a first direction on a firstconductive layer and a plurality of non-continuous conductive linesarranged in a second direction on a second conductive layer; selecting aplurality of first conductive lines from the plurality of non-continuousconductive lines; selecting a plurality of second conductive lines fromthe plurality of non-continuous conductive lines; and replacing theplurality of second conductive lines by a plurality of third conductivelines respectively when the plurality of first conductive lines and theplurality of second conductive lines are assigned to a first mask,wherein the plurality of third conductive lines is assigned to a secondmask different from the first mask layer.

According to some embodiments, a system is provided. The at least oneprocessor is configured to execute program instructions which configurethe at least one processor as a processing tool that perform operationscomprising: forming, by the processing tool, a conductive grid on asemiconductor substrate, wherein the conductive grid has a plurality ofcontinuous conductive lines arranged in a first direction on a firstconductive layer and a plurality of non-continuous conductive linesarranged in a second direction on a second conductive layer; selecting,by the processing tool, a first conductive line and a second conductiveline from the plurality of non-continuous conductive lines, wherein aspace between the first conductive line and the second conductive linehas a first width; selecting, by the processing tool, a third conductiveline and a fourth conductive line from the plurality of non-continuousconductive lines, wherein the space between the third conductive lineand the fourth conductive line has a second width; and replacing, by theprocessing tool, the third conductive line and the fourth conductiveline by a fifth conductive line and a sixth conductive linerespectively, wherein the space between the fifth conductive line andthe sixth conductive line has the first width, and the second width isgreater than the first width.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A method of forming an integrated circuit: forming a conductive grid on a semiconductor substrate, wherein the conductive grid has a plurality of continuous conductive lines arranged in a first direction on a first conductive layer and a plurality of non-continuous conductive lines arranged in a second direction on a second conductive layer; selecting a plurality of first conductive lines from the plurality of non-continuous conductive lines according to a first mask layer assigned to the plurality of first conductive lines; selecting a plurality of second conductive lines from the plurality of non-continuous conductive lines according to a second mask layer assigned to the plurality of second conductive lines, wherein the second mask layer different from the first mask layer, and the plurality of second conductive lines is electrically connected to the plurality of first conductive lines via the plurality of continuous conductive lines; and replacing the plurality of second conductive lines by a plurality of third conductive lines respectively when the plurality of first conductive lines has a cut-metal pattern and the plurality of second conductive lines does not have the cut-metal pattern, wherein the plurality of third conductive lines is assigned to the first mask layer.
 2. The method of claim 1, wherein the first direction is orthogonal to the second direction, and the first conductive layer is different from the second conductive layer
 3. The method of claim 1, whereineach of the plurality of second conductive lines comprises: a first end and a second end, and the first end and the second end are not connected by the cut-metal pattern.
 4. The method of claim 1, whereineach of the plurality of third conductive lines comprises: a first cut-metal pattern connected to a first end of the third conductive line; and a second cut-metal pattern connected to a second end of the third conductive line.
 5. The method of claim 1, wherein each of the plurality of first conductive lines comprises: a first cut-metal pattern connected to a first end of the first conductive line; and a second cut-metal pattern connected to a second end of the first conductive line.
 6. The method of claim 1, wherein each of the plurality of third conductive lines is shorter than each of the plurality of second conductive lines.
 7. The method of claim 1, wherein a plurality of fourth conductive lines is disposed between the plurality of first conductive lines and the plurality of second conductive lines, the plurality of fourth conductive lines is assigned to the second mask layer, and the plurality of fourth conductive lines is not electrically connected to the plurality of first conductive lines and the plurality of second conductive lines.
 8. The method of claim 7, whereineach of the plurality of fourth conductive lines comprises a first end and a second end, and the first end and the second end are not connected by the cut-metal pattern.
 9. The method of claim 7, wherein a first continuous conductive line in the plurality of continuous conductive lines is electrically coupled to the plurality of first conductive lines and the plurality of second conductive lines, a second continuous conductive line in the plurality of continuous conductive lines is electrically coupled to the plurality of fourth conductive lines, and the first continuous conductive line is different from the second continuous conductive line.
 10. A method of forming an integrated circuit: forming a conductive grid on a semiconductor substrate, wherein the conductive grid has a plurality of continuous conductive lines arranged in a first direction on a first conductive layer and a plurality of non-continuous conductive lines arranged in a second direction on a second conductive layer; selecting a plurality of first conductive lines from the plurality of non-continuous conductive lines; selecting a plurality of second conductive lines from the plurality of non-continuous conductive lines; and replacing the plurality of second conductive lines by a plurality of third conductive lines respectively when the plurality of first conductive lines and the plurality of second conductive lines are assigned to a first mask, wherein the plurality of third conductive lines is assigned to a second mask different from the first mask layer.
 11. The method of claim 10, wherein the first direction is orthogonal to the second direction, and the first conductive layer is different from the second conductive layer.
 12. The method of claim 10, whereineach of the plurality of first conductive lines comprises a first end and a second end, and the first end and the second end are not connected by a cut-metal pattern.
 13. The method of claim 10, wherein each of the plurality of second conductive lines comprises a first end and a second end, and the first end and the second end are not connected by a cut-metal pattern.
 14. The method of claim 10, wherein each of the plurality of third conductive lines comprises: a first cut-metal pattern connected to a first end of the third conductive line; and a second cut-metal pattern connected to a second end of the third conductive line.
 15. The method of claim 10, wherein each of the plurality of third conductive lines is shorter than each of the plurality of second conductive lines.
 16. The method of claim 10, wherein a first continuous conductive line in the plurality of continuous conductive lines is electrically coupled to the plurality of first conductive lines, a second continuous conductive line in the plurality of continuous conductive lines is electrically coupled to the plurality of second conductive lines, and the first continuous conductive line is different from the second continuous conductive line.
 17. A system, comprising: at least one processor, configured to execute program instructions which configure the at least one processor as a processing tool that perform operations comprising: forming, by the processing tool, a conductive grid on a semiconductor substrate, wherein the conductive grid has a plurality of continuous conductive lines arranged in a first direction on a first conductive layer and a plurality of non-continuous conductive lines arranged in a second direction on a second conductive layer; selecting, by the processing tool, a first conductive line and a second conductive line from the plurality of non-continuous conductive lines, wherein a space between the first conductive line and the second conductive line has a first width; selecting, by the processing tool, a third conductive line and a fourth conductive line from the plurality of non-continuous conductive lines, wherein the space between the third conductive line and the fourth conductive line has a second width; and replacing, by the processing tool, the third conductive line and the fourth conductive line by a fifth conductive line and a sixth conductive line respectively, wherein the space between the fifth conductive line and the sixth conductive line has the first width, and the second width is greater than the first width.
 18. The system of claim 17, wherein the first conductive line, the second conductive line, the fifth conductive line, and the sixth conductive line are assigned to a first mask layer, and the third conductive line and the fourth conductive line are assigned to a second mask layer different from the first mask layer.
 19. The system of claim 17, wherein the first direction is orthogonal to the second direction, and the first conductive layer is different from the second conductive layer.
 20. The system of claim 17, wherein a first continuous conductive line in the plurality of continuous conductive lines is electrically coupled to the first conductive line and the third conductive line, a second continuous conductive line in the plurality of continuous conductive lines is electrically coupled to the second conductive line and the fourth conductive line, and the first continuous conductive line is electrically connected to the second continuous conductive line. 